No Spam wrote:
On Thu, 16 Dec 2004 06:27:16 UTC, Edward Knobloch
wrote:
You really don't need receiver muting for c.w. QSK,
just a receiver who's AGC can be turned off, or is very fast.
..
the receiver's input stage. The signal is still loud, but if you
switch the AGC off, you can hear a breaking station between dits.
Thanks. I'd prefer to something more like Tentec's concept of QSK
and not listen to a thumping receiver or hammer my S-meter against
the pin.
Done right, QSK is a delight.
I think it can be done with off-the-shelf pieces. Looks like the
key is the www.radioadv.com keyer-TR switch and just about any QRP
transmitter kit, or at least that's what folk are telling me.
de ah6gi/4
I fully agree with you that, done right, QSK is a delight. I have been
using a Heathkit HR-1680/HX-1681 combination for over 20 years now.
The QSK works extremely well. It is virtually imperceptible that the
receiver is actually being shut down during my dots and dashes. There
is no thumping or bumping or hammering of the S-Meter, and I can hear
all of the band activity.
IMHO, I think that to have a good QSK setup, you must take the capabilities
of both the receiver and transmitter into account. This Heathkit pair
was designed to work together. There is a keying circuit inside that
controls the timing of the receiver muting, transmitter keying, and
T/R switch operation. No relays are involved at all. The low level
keying and frequency generation is all solid state and the final (tubes)
is run Class AB2, for a nice clean, well shaped, signal.
It may be beneficial to get a copy of the HX-1681 transmitter and
investigate how they implemented it. I haven't looked at the schematic
in a long time but I don't think it was very complicated. It may be
similar to Tentec's concept of QSK.
I also seem to remember that in the ARRL Handbook, 2000 I think,
there was a project for making implementing automatic T/R switching
for vintage transmitters and receivers. I don't remember if they went
into full QSK, or not, but it's another possible resource.
--
Martin E. Meserve - K7MEM
http://www.k7mem.com